1. Field of the Invention
The present invention relates to a waste disposal process in which waste material is completely renewed to useful matters applying oxygen enriched gas(pure oxygen+Steam+CO2 gas) instead of air, thus allowing to accomplish emission free closed system and be able to eliminate conventional stack(source of pollution) and achieved innovative overall process performances.
2. Description of the Related Art
AS is well known, trash or waste material created from a variety of sources have been finally disposed by way of earth filling or incineration.
Such a conventional incineration process of waste material burns by the air under assist of auxiliary fuel burner, then produce flue gas and non-combustible residues.
Then, any hazardous substance contained in the flue gas thusly produced combustion gas is purged and discharged at a level pursuant to rules and regulations imposed by the government. Non-combustible inorganic matter including the combustion residue, particulate matter and waste additive is collected and solidified for earth filling. The combustion heat generated during the combustion process can be collected for a reuse in a boiler.
FIG. 1 illustrates a conventional waste incineration system, wherein a first combustion furnace(1) burns a solid waste substance using the air and a second combustion furnace(2) fires the exhaust gases containing combustible gas and particulate matter. And the combustion heat collected as a steam by latent heat of vaporization of water in a boiler(3). A post-treatment process(4) eliminates hazardous gases and dusts to satisfy a level imposed by the rules and regulations imposed by the government, and the flue gas finally exhaust to the atmosphere through a stack(5). The first and second combustion furnace(1) and (2) may exist in a single incinerator or in incinerators separated from each other. However, physical structure of the combustion chambers reflects an excellent mixture of combustion gases therein.
In the post-treatment process(4), SOx, HCl, NOx, and dusts of hazardous material contained in the flue gas are primarily eliminated, together with an extremely small amount of dioxin, mercury, and heavy metals. As a method of elimination, a neutralization-adsorption-filtering method utilizing a hydrated lime and an activated carbon powder is employed. A selective catalytic reaction method under a small amount of ammonia injection is additionally employed for elimination of nitrogen oxide(NOx) and dioxin.
In particular, conditions of combustion time period of at least 2 seconds and combustion temperature of 850xc2x0 C. or higher are required to be maintained for a complete decomposition of hazardous materials contained in the flue gas, namely, dioxin. For this reason, an auxiliary burner is arranged in the second combustion furnace(2) for support insufficient heat amount of waste material or excessive wetness.
In case of the time band of the steam generating from boiler, do not overlap to the time band of users, the steam commonly used as power source for generation electric power by means of steam turbine-generating systems, and the power utilized as self requirements, while the excess power transmitted to the public network of power. However, since the overall efficiency of power generation is significantly lower than the commercial power plant, thereof this systems are generally neglected due to economical reasons.
Such a conventional waste disposal method suffers drawbacks in that hazardous gases may be exhaust via a chimney, which causes a variety of damages and inconveniences in human life in addition to the following problems.
First, the discharged hazardous substance including dioxin which is not decomposed is scattered and accumulated in the nature since the conventional system employs a low pollution process, not a completely pollution-free process.
Second, the only gain from the waste disposal is use of collected heat in the boiler and the amount of the heat is extremely small. Therefore, a high level technique for eliminating of hazardous material may not be applied.
Third, a large volume of unnecessary nitrogen should be introduced since air is used as an oxygen supply source. Thus, hazardous gas, namely, thermal nitrogen oxide(NOx) is generated, and a large sized apparatus is needed, increasing in operation and construction cost. In addition, thus-generated hazardous material is diluted by a large volume of nitrogen, resulting in low performance of elimination of hazardous material in post-treatment process, lowering an overall process efficiency.
Therefore, it is an object of the present invention to provide a stackless and emission free waste disposal process in which an oxygen enriched gas is utilized for a complete renewal of the waste material.
To accomplish the above object of the present invention, there is provided a waste material disposal process in which a conventional process of using a combustion chamber is replaced with a process of using a melting-low temperature thermal decomposition fumace(21) having a unique and simple configuration, and a process of using a low temperature catalyst-combustion process(24) or high temperature catalyst steam reforming process(25). And a high grade purification process(22) for removal of hazardous gases and a process(23) of reclaiming the generated waste water utilizing a special low temperature catalytic oxidation are inserted right after melting-low temperature thermal decomposition furnace(21).